Head suspensions for supporting a head over a rotating disk in hard disk drives are well known. Such head suspensions typically comprise a load beam having a flexure or gimbal at its distal end. A head slider having a read/write transducer is mounted to the flexure. In operation, the rotating disk creates an air bearing on which the head slider floats. The head suspension provides a spring force counteracting the force generated by the air bearing to position the slider at a specified “fly height”. The flexure is sufficiently compliant to allow the slider to pitch and roll in response to fluctuations in the air bearing created by variations in the surface of the rotating disk. In this manner, the head slider is supported and can be positioned over the disk by an actuator assembly driven by a voice coil motor to read or write information on the data tracks of the disk.
As the trend to pack more data onto every square inch of the disk surface continues, the head suspension needs to track more precisely and the slider needs to fly closer to the disk surface. In order to track more precisely, the resonant characteristics of the suspension must improve; i.e. a stiffer suspension is required. Counteracting the need for a stiffer suspension is the need for lower spring forces and thus thinner suspension components to accommodate lower fly heights.
Stiffening rails, to transfer the spring force of the suspension to the slider and to increase the resonance frequencies of the suspension, are also well known. Conventional stiffening rails, such as disclosed in U.S. Pat. Nos. 5,198,945 to Blaeser et al.; and 6,313,970 to Pace et al., do not provide adequate resonance characteristics for thin suspension components.
There is a continuing need for improved stiffening rails in head suspensions. Specifically, there is a need for a rail structure that increases resonance frequency modes in thin suspension components. To be commercially viable, such rails should be capable of being efficiently and accurately manufactured.